class Counter{
    private int count=0;

    public void add(){
        count++;
    }

    public int get(){
        return count;
    }
}

public class demo05 {
    public static void main(String[] args) throws InterruptedException {
        Counter counter=new Counter();

        //创建两个线程分别对counter自增50000次
        Thread t1=new Thread(()->{
            for (int i = 0; i < 50000; i++) {
                counter.add();
            }
        });

        Thread t2=new Thread(()->{
            for (int i = 0; i < 50000; i++) {
                counter.add();
            }
        });

        t1.start();
        t2.start();

        t1.join();
        t2.join();
        //结果不为100000！！！
        System.out.println(counter.get());
    }
}
